I'm just starting a new Spec Boxster build and have a question about removing the CAT's. I know if I remove the CAT's when I switch to a lighter race exhaust, I will get CEL's (check engine lights). And Spec Boxster rules say I can't reprogram the ECU. Is this a problem? (other than having to cover up the light) Will the engine still run correctly, or will it go into some kind of "limp mode"?

 

It will run fine. I removed my cats ('98 with one set of cats), the first set of O2 sensors are in the headers and the 2nd set I have zip tied up in the body work. Since they are still sampling the air they're kind of being tricked that all is well, sort of. Every now and then on a long highway drive (usually to the Glen) the CEL lights up and in 1 minute i have it cleared with the app on my phone that is connected via a bluetooth OBD transmitter. Yes I street drive my SPB to the track.

Taping up the light will work too but you won't know if something actually serious might be happening, I still pucker a little when it comes on but it's always the O2 sensor.

A good Porsche race shop might be able to get the "Learning codes" from a friendly Porsche dealer and have your ECU flashed with the ROW tune which is legal by the rules. All it does is ignore the O2 and SAI sensors.

Side Note: I've been told the tip of the O2 sensor gets intentionally super hot, so be careful where you place it and that the tip is not touching anything.

 

Pretty much agree with BFT3.2 -- The car will run fine with the secondary O2 sensors tied out of the way breathing fresh air. Although, in my experience, CEL will not be triggered by this. (I eventually did get a CEL at some point, but because the sensor had indeed gone bad! Come to think of it, it may have been the forward sensor.)

 

Disconnect them, no need. no limp mode.